The National Audit Office certified European Standard for the onset of old age is the inability to hop. Or it should be. "Hop" is an abbreviation of "high pop", which is when something rises rapidly into the air, mostly on one leg, driven by some internal pressure such as exhilaration or a burning sensation in the other foot.

Before the advent of computer games involving evisceration, mutilation and obliteration, children spent a lot of time hopping. Hopscotch was the Nintendo DS of most children born before 1970. As children grew up they were then taught to stand on their own two feet, which put a stop to hopping.

Hopping is what happens when you always put your best foot forward. It's not an ideal form of locomotion, which is why there are so few one-legged animals. Grasshoppers don't hop. They're actually grassjumpers. Similarly, planes making short hops don't take off on one wheel.

Everything that moves on one foot does so with a slight air of foolishness: witness the unicycle, pogo stick and space hopper. One reason the seahorse looks so unnerving is that it clearly has only one leg/foot and moves through the sea in a kind of aquahop. Robots have been developed that are clever enough to walk. The real challenge is to make them foolish enough to hop.

When people get really angry they are said to be hopping mad. Angry people don't in fact hop, and this is actually an optical illusion. What they do is stamp their feet, giving the impression they're about to hop without ever lifting off.

You're more likely to hop when you're very happy. When you've just asked somebody you really fancy to go out and they've said yes, you'll find as you walk away an overwhelming compulsion to put a little extra hop in your walk. This is known as having a spring in your step. Beer gives you a similar lift because it is made from hops.

Young children hop into bed. Adults do bed-hopping, which is an entirely different thing. Rich people with yachts do island hopping. Anything fun that you do in little chunks can be described as hopping. Except hot-desking, which is far too serious to be called desk-hopping.